Technology includes many devices which include a rotating shaft which is supported by some bearing means and wherein the rotating shaft, at the point of bearing, is immersed in a liquid. Such devices present unique problems regarding the type of bearing support to be utilized.
More conventional metallic roller and ball bearings prove to be inappropriate for support in view of the environment in which the bearing functions. Because of the metallic nature of the structures, corrosion tends to be high, thus rendering the bearing inoperative. Use of metallic alloys highly resistant to corrosion tends to alleviate some of the deterioration problems, but bearings so constructed tend to be expensive.
One particular application of a rotating shaft supported by a bearing structure in a liquid is the apparatus used for aerating liquid waste as disclosed by patent application for an apparatus for mixing a gas and a liquid, Ser. No. 898,983, filed Apr. 21, 1978, now abandoned. Other problems exist with this particular application of such a device. The liquid environment in which such a device is used contains quantities of sedimentary solids, and, when the mixing action is induced, those sediments are dispersed throughout the liquid and are introduced at the bearing. When roller or ball bearings are used (even ones which resist corrosion), the sediments tend to clog and bind the bearing and, thereby, render it ineffectual.
Because of these problems, a differently structured bearing is utilized to provide the support for the rotating shaft. An encircling structure provides the support for the shaft, and the lubrication therebetween is provided by the liquid environment itself. Application of an aqueous film to the shaft where the shaft engages the bearing surface is facilitated, and friction between the shaft and bearing is, thereby, reduced.
Typically, these bearings have been constructed as an annular collar mounted within a housing and encircling the rotating shaft. On the inner surface of the collar are formed a multiplicity of circumferentially spaced axially extending channels. It has been felt that frequent circumferential spacing of these channels is necessary in order to provide adequate flow of lubricative fluid. A common substance from which the inner surface of the collar bearing has been made is Teflon in order to preclude problems of corrosion as with metallic bearings.
As in the case with roller bearings and ball bearings, the agitated sediment remains a problem. It has been ascertained that, in this type of device, forces will tend to induce a flow of the environmental liquid up through the bearing. Bearings currently in use permit flow through the bearing at too great a volume and at too fast a rate of flow. Consequently, large volumes of sediment pass through the bearing and may cause clogging or scoring and subsequent deterioration of the bearing.
Applicant's invention provides a structure which solves the problems existent in the art.